One possible plot could be that the UNSC discovers a derelict Xenomorph-infested ship while on a routine exploration mission in Halo space. The Spartan soldiers have to fight off the Xenomorphs while also trying to figure out how they got there and if there's a connection to the Forerunners. Maybe the Xenomorphs are being used as some sort of biological weapon by an unknown faction.
Well, a cool plot might involve a group of Marines getting stranded on a planet that has both Covenant and Xenomorph threats. The Marines have to team up with some Elites who also want to survive the Xenomorph attacks. They then discover that the Covenant is actually trying to harness the Xenomorphs' power for their own purposes, and the Marines and Elites have to stop them while also dealing with the Xenomorphs.
In a fanfic, the Halo characters would interact with Xenomorphs in various ways. The Spartans, being super - soldiers, would be the front line against the Xenomorphs. They would study the Xenomorphs' movements and attack patterns. The Covenant races would have different reactions. The Jackals might try to snipe at the Xenomorphs from a distance, while the Hunters would use their brute strength. But overall, it would be a chaotic and dangerous interaction as the Xenomorphs' acid blood and stealthy attacks would pose a great threat to all the Halo characters.
Well, one possible plot could be that Naruto somehow stumbles upon a portal or a hidden area in the Naruto world where Xenomorphs exist. Maybe Orochimaru was doing some forbidden experiments and accidentally opened a gateway to their dimension. Naruto, being the curious and brave ninja he is, decides to explore. He then has to use his ninja skills like his shadow clones and rasengan to fend off the Xenomorphs. He might also try to find a way to close the gateway to prevent the Xenomorphs from spreading across the ninja world.
One idea could be that the Master Chief somehow gets transported to Skyrim. He could use his advanced combat skills and high - tech weaponry in the medieval - like setting of Skyrim. For example, facing off against dragons with his energy sword, creating a really cool contrast between the high - tech and the fantasy elements.
Maybe the Forerunners in the Halo universe somehow cross paths with the Dust - the energy source in RWBY. This could lead to a power struggle or an alliance based on the unique properties of Dust. The characters from RWBY might use their Semblances in combination with Halo technology for some really cool battles.
One possible plot could be that Percy and his demigod friends are somehow transported to the Halo universe. They could team up with the Spartans to fight a common enemy, like a new kind of powerful monster that has emerged in the Halo world due to some strange rift between the two universes. Percy could use his water powers in unique ways, for example, to short - circuit some of the Covenant technology which might be vulnerable to water in this crossover scenario.
Well, it's interesting because it allows for new character interactions. Imagine a Spartan from Halo teaming up with Ruby from RWBY. Their different skills and personalities would make for an engaging story. Also, the contrast between the two universes' aesthetics, like the gritty, mechanical look of Halo and the more colorful, anime - inspired RWBY, adds to the appeal. Fans of both can see how their favorite elements mesh together, whether it's the Covenant vs the Grimm or the Spartans using their advanced weaponry in the RWBY world.
A unique take on the crossover concept. For example, if it combines the dark, gritty atmosphere of Doom with the epic sci - fi world of Halo in a creative way. Maybe it has the Doomguy in the Halo universe facing off against Covenant forces, that would be really cool.
One possible plot could be that Harry Potter, instead of being raised by the Dursleys, is found by Xenomorphs. Maybe the Xenomorphs sense his magic and decide to protect him in their own strange way. They could teach him skills that are a blend of wizardry and Xenomorph - like survival instincts. For example, he might learn to use his magic to communicate with the Xenomorphs on a deeper level and in turn, they could teach him how to move stealthily and sense danger in a way that wizards usually don't.
One interesting crossover could be Master Chief meeting Iron Man. They are both iconic in their own universes. Master Chief with his Spartan strength and combat skills, and Iron Man with his high - tech suits. They could team up to face a common enemy that threatens both the Halo and Marvel universes, like an interdimensional threat that is after the advanced technology in both worlds.
Perhaps in the 'naruto x batman fanfic', there's a threat that endangers both the Naruto world and Gotham at the same time. A powerful interdimensional villain is causing chaos. Naruto and Batman meet in a neutral dimension and have to quickly learn to trust each other. Naruto teaches Batman about chakra control to enhance his combat skills, while Batman shows Naruto how to use gadgets and strategic thinking to outwit their enemy.